中文摘要：

利用微层共挤出技术制备得到不同层数（2、4、16和64层）的聚丙烯（PP）/阻燃剂（IFR）填充PP（PPFR）交替层状复合材料,研究了层数改变对复合材料阻燃和力学性能的影响.偏光显微镜观察发现,PP层与PPFR层沿层状样品的厚度方向交替排布,层界面则随着层数的增加而增多.非等温结晶测试结果显示,界面的增多使更多的IFR可以分布在层界面附近,使整个层状复合体系表现出越来越接近传统IFR填充体系的异相成核结晶行为,表明IFR的分布可以通过层数的调节进行调控.垂直燃烧、极限氧指数（LOI）以及微型量热测试结果表明,层数提高可以有效提高复合体系自熄能力,显著降低热释放速率.与2层试样相比,64层试样的LOI从19.5提高到了25.而拉伸性能测试结果显示,随着层数增加,复合材料的拉伸强度变化较小,但断裂伸长率显著提高.

英文摘要：

Polypropylene（ PP） /intumescent flame retardant（ IFR） filled PP（ PPFR） alternating multilayered composites with different layer numbers（ 2,4,16 and 64） were fabricated through a layermultiplying coextrusion technology. The influence of the number of layers on the flame-retarding and mechanical properties of the multilayered specimens was investigated. Polarized light micrographs displayed that PP and PPFR layers were distributed alternatively along the thickness direction of the multilayered specimen,and interfaces between PP and PPFR layers were enriched with increasing the number of layers. The non-isothermal crystallization curve of the specimen with more layers tended to become similar to that of the conventional IFR-filled system,which was ascribed to the heterogeneous crystallization of PP layers induced by IFR particles located around interfaces. This suggested that the distribution of IFRs could be controlled by changing the number of layers. The results of vertical burning test,LOI and MCC showed that increasing the number of layers could play a positive role in accelerating the self-extinguishment of an ignited specimen and decreasing its heat release rate. Compared with that of the 2-layer specimen,the LOI of 64-layer specimen was increased from 19. 5 to 25. Tensile properties displayed that increasing the number of layers little influenced the tensile strength of multilayered specimens,while induced a significant increase of the elongation at break. It was considered that the multilayered distribution of IFRs could not only promote the formation of continuous char layers,but also retard the propagation of crazes in the whole composites. Thus,it would be a novel route to fabricate polymer composites with both excellent flame retardancy and mechanical properties.